Mix tracks in the Audio Mixer

You can set volume levels of two or more audio tracks, relative to one another, using the Audio Mixer. For example, you can raise the volume of a narrator’s voice on one audio track while simultaneously decreasing the volume of the background music on another track. Also, you can raise or lower the overall volume level of the complete mix, which contains the audio from all tracks selected. The Audio Mixer lets you make these adjustments in real time while you listen to playback from desired tracks. By default, the Audio Mixer volume adjustments made for each audio track are saved in Track Volume keyframes visible on that track in a Timeline panel. Volume adjustments made for the whole mix are saved in Track Volume keyframes visible in the Master audio track in a Timeline panel.

Select a sequence that contains audio in two or more audio tracks.
Select Window > Workspace > Audio.
The Audio Mixer panel appears in the central drop zone, with each audio track of a Timeline panel assigned to its own bus on the mixer.
In a Timeline panel, for each audio track, click the Show Keyframes button . Then choose Show Track Volume from the drop-down menu.
Toward the bottom left of the Audio Mixer panel, click the Play button to play the sequence and monitor its audio.
Move the volume slider for any audio track up or down to increase or decrease its volume as you monitor the sound.
Move the volume slider for the Master track up or down to increase or decrease the volume of the whole mix as you monitor the sound.

Track Volume keyframes appear in each of the tracks for which you made volume adjustments, including the Master track.